Design, synthesis, and evaluation of substrate - analogue inhibitors of Trypanosoma cruzi ribose 5-phosphate isomerase type B.
Gonzalez, S. N., Mills, J. J., Maugeri, D., Olaya, C., Laguera, B. L., Enders, J. R., Sherman, J., Rodriguez, A., Pierce, J. G., Cazzulo, J. J. and D'Antonio, E. L.
Instituto de Investigaciones Biotecnologicas, Universidad Nacional de General San Martin - CONICET (IIBio-UNSAM), Avenida 25 de Mayo y Francia CP (1650), San Martin (Buenos Aires), Argentina.
Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Box 8204, Raleigh, NC 27695, USA.
Department of Natural Sciences, University of South Carolina Beaufort, 1 University Boulevard, Bluffton, SC 29909, USA.
Molecular Education, Technology and Research Innovation Center (METRIC), North Carolina State University, Raleigh, NC 27695, USA.
Department of Microbiology, New York University School of Medicine, 430 East 29(th) Street, New York, NY 10016, USA.
Department of Natural Sciences, University of South Carolina Beaufort, 1 University Boulevard, Bluffton, SC 29909, USA. Electronic address: edantonio@uscb.edu.
Ribose 5-phosphate isomerase type B (RPI-B) is a key enzyme of the pentose phosphate pathway that catalyzes the isomerization of ribose 5-phosphate (R5P) and ribulose 5-phosphate (Ru5P). Trypanosoma cruzi RPI-B (TcRPI-B) appears to be a suitable drug-target mainly due to: (i) its essentiality (as previously shown in other trypanosomatids), (ii) it does not present a homologue in mammalian genomes sequenced thus far, and (iii) it participates in the production of NADPH and nucleotide/nucleic acid synthesis that are critical for parasite cell survival. In this survey, we report on the competitive inhibition of TcRPI-B by a substrate - analogue inhibitor, Compound B (Ki = 5.5 +/- 0.1 muM), by the Dixon method. This compound has an iodoacetamide moiety that is susceptible to nucleophilic attack, particularly by the cysteine thiol group. Compound B was conceived to specifically target Cys-69, an important active site residue. By incubating TcRPI-B with Compound B, a trypsin digestion LC-MS/MS analysis revealed the identification of Compound B covalently bound to Cys-69. This inhibitor also exhibited notable in vitro trypanocidal activity against T. cruzi infective life-stages co-cultured in NIH-3T3 murine host cells (IC50 = 17.40 +/- 1.055 muM). The study of Compound B served as a proof-of-concept so that next generation inhibitors can potentially be developed with a focus on using a prodrug group in replacement of the iodoacetamide moiety, thus representing an attractive starting point for the future treatment of Chagas' disease.
Bioorganic and Medicinal Chemistry Letters 32: 127723 (2021)